


Playing the Doctor Game

by rehliamonster



Series: The Games Series [3]
Category: Undertale (Video Game)
Genre: Aftercare, BDSM Scene, Breeding Kink, Consensual Non-Consent, Everything is consensual and agreed on, F/M, Medical Examination, Medical Kink, Medical Play, Monster sex, Non-Consensual Drug Use, Oneshot, Orgasm Delay/Denial, PWP, Plot What Plot/Porn Without Plot, Rape Play, Reader-Insert, Shameless Smut, Vaginal Fingering, but it reads like straight noncon at first so read at your own risk, fertility drugs, forced impregnation, reader is female
Language: English
Status: Completed
Published: 2017-01-08
Updated: 2017-01-08
Packaged: 2018-09-15 20:55:31
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,178
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/9256907
Author URL: https://archiveofourown.org/users/rehliamonster/pseuds/rehliamonster
Summary: Gaster has his way with you in his laboratory.





	

You wake up dizzy, confused and cold. There’s a blinding light above you that forces your eyes shut immediately as you try to open them, the brightness painful after just waking up. The air is stale and smells like chemicals. A shiver runs down your body and you can feel goosebumps spreading on your skin. The surface you’re lying on his cool and feels like leather. Instinctually, you try to curl up to preserve body heat, but you find that you can’t move. 

A gasp escapes you when your limbs are met with resistance at your wrists and ankles, something thick digging into your skin. Each movement produces noise, the creak of leather and the clatter of metal. You’re strapped down. You can’t move and your legs - 

Your legs are spread and held up, you’re cold, you’re _naked_ \- 

“Awake?”

The voice is low, quiet and smooth, speaking in a way that sounds clinical and detached. It does nothing to help the situation. 

“Good. Then I can finally begin.”

“W-what? Wait! Who are you?!” You demand to know. You try to blink your eyes open again and this time you manage to get used to the bright light. 

You’re strapped onto a gynecologist examination table, held down by thick, broad leather straps with your legs spread and your arms tied down next to your torso. Apart from the straps on your wrists and ankles, there are also several holing your thighs and arms down, and you feel one across your neck too. A clip has been placed on one of your toes, with a cable running to a monitor that displays your vitals, inset into a wall with white tiles. The entire room seems to be covered in white tiles. A peripheral venous catheter is sticking out of the skin in the crook of your left arm, held in place by several strips of adhesives. You follow the thin tube connecting to it up to an IV bag hanging from a pole. 

Something’s dripping into you. 

“What is that?!” You ask in a panicked tone of voice.

You look around frantically. 

To your right, you can see a flat steel tray on a small utility table, with several tubes, syringes and other medical instruments on it. Behind it, a tall man… no, not a man. 

The creature behind the utility table is a solid mass of black, something that looks like a mixture of slime and smoke, solid at the centre and wispy like fog at the edges of his form. His head and hands are the only things about him that are white and both are damaged; two deep cracks run over the top of his right and the underside of his left eye, and there are large, round holes in the palms of his skeletal looking hands. His mouth is a black gash across his face and there are tiny lights floating in the gaping black holes that are his eyes. A lab coat covers his arms and torso, although it’s open at the front, revealing most of his body and a thick erection, a writhing tentacle with a tapered tip that keeps reaching in your direction. He’s holding a clipboard and a pen, writing something down on a piece of paper. 

“I believe the drug should already be taking effect,” the creature states calmly, putting the clipboard and the pen down. “Describe to me how you are feeling, subject five.”

“What do you mean, drug?!” You try again to move your limbs, testing the leather straps to see if maybe you can pull out of your restraints. They are pulled too tight though, and you are left to struggle helplessly. 

“Don’t waste your energy,” the creature states. “I am most careful in how I handle my test subjects. It would be too much of a setback if you escaped or hurt yourself. As for the drug, I have administered a simple aphrodisiac to get things started.”

“Aphro… to get what started? Who _are_ you?”

“The insemination process, of course. I suppose the shock and the sleeping pills must have affected your memory…” The creature looks down at your fearful face with a thoughtful expression. “Allow me to remind you. My name is Doctor Gaster. You may address me as ‘Doctor’ or as ‘Doctor Gaster.’ You are test subject five of my research facility and we are currently in my personal laboratory. I am the leading researcher for monsterkind, and I have been tasked to conduct an experiment to see if it is possible for you to be bred and produce a monster-human hybrid.”

“What the fuck! No! Let me go!”

“I am afraid your opinion as a test subject is irrelevant. A hybrid would allow us a lot of insight into the intricacies of how human and monster biology interact… such a chance cannot be passed upon. If you do not cooperate, I will simply have to use force. Do not take it personally. Sacrifices must be made in the name of science.”

“I don’t care about your fucking science! Let me go!”

Instead of answering, Doctor Gaster picks up a pair of rubber gloves and pulls them over his hands. He approaches the medical chair you’re strapped onto and presses his gloved hands to your forehead. You try to move your head away by turning it to the side, but you have so little room for movement that it doesn’t really help. 

“Slightly increased temperature,” Doctor Gaster proclaims. 

His hands move down to your breasts and he begins examining them, feeling their weight and pushing the fingers into their sides. 

“Mild swelling in the breasts.” 

“Stop it!”

He gives your breasts a mild squeeze and then moves down along the medical chair until he’s standing between your legs. Your breath quickens and you immediately try to close your legs, despite knowing that the straps are too secure for you to move. A hiss escapes you when you feel the gloved hands on your outer labia, pulling them gently apart. 

“Hmmm.” Doctor Gaster looks down thoughtfully. He bends over and brings his face closer to your vulva. You can feel his breath ghosting against the sensitive flesh.

“N-no, don’t look! Stop!”

“Inadequate lubrication,” he states calmly. “I suppose the drug can only do so much. No matter. I can help you along until you get to the right amount.” 

He removes himself and moves over to the utility table, picking up a tube and squeezing some of the contents onto two of his gloved fingers. It appears to be some sort of lubricant. He rubs his fingers together and spreads the lube onto the rest of his fingers, before deciding to apply some more out of the tube. Only when all of his gloved fingers are thickly covered and glistening under the bright light of the lamp overhead does he return to his position between your legs. 

“Now, relax if you can.” Doctor Gaster brings the lube-coated fingers back to your labia. You shudder when you feel the wet rubber of the gloves make contact with your skin. He begins to stroke his fingers up and down along your slit before focusing on your clitoris. Slow, languid, circling motions, building up a steady rhythm. You whimper quietly. 

“There, very good. Just a little bit more.” His fingers move lower again. The gentle motions on your clit have started to make you wet, and so when he presses a finger against your entrance it slides in easily, helped along by the lube and your own juices. He starts pumping in and out, taking care to rub against your walls here and there. It sends shivers through your body whenever he does.

“If there is anything else I can do to make the procedure more pleasurable for you, please let me know,” Doctor Gaster explains, all the while keeping his finger pumping in and out of you. “The contractions during orgasm are actually designed to help the insemination process along, you know. The vaginal walls and the cervix are moving specifically to push and suck the semen into the uterus. It is in our mutual interest that you achieve climax. For me, it means that the chances of impregnation increase significantly. I imagine that you also prefer it to having a more painful experience.”

“I want to you to stop,” you say, almost choking on your words. Your body is betraying you in response to his gentle motions, heat building in your stomach and your core. 

“That is not possible. But do not worry. I will do my best to ensure a satisfactory climax and swift impregnation, subject five.”

You whine as he adds a second finger, pumping faster now and occasionally spreading his fingers, scissoring you open and stretching you. Then he curls his fingers upwards, deliberately moving against the flesh until he hits that one spot inside you that sends a burning heat through you. 

A loud moan echoes through the small room. 

“Ah. There it is. I am glad I found it, I believe this will help us achieve your climax much better.”

“Please.” You don’t know what you’re begging for at this point, but the doctor interprets it in the most convenient way for him.

“Of course.” 

His fingers curl again and your spine arches as far as it can before the restraints on your arms, legs and neck prevent further movement. Your moans start getting louder and more breathless as he repeats that motion inside of you, interspaced here and there by more scissoring. Eventually, he adds a third finger and you almost scream. The jolts of pleasure become unbearable. Just before your climax hits, his fingers pull out. 

You lie still in your medical chair, raggedly breathing, tears stinging in your eyes. You want to come and you know that’s wrong. You feel dirty. 

“I believe you are now ready for the actual insemination process,” Doctor Gaster says calmly. 

“N-no, please - “

Completely ignoring your protest, he steps closer and lines himself up. The thick tentacle that appears to be his penis doesn’t need his guiding hand to find its way inside of you. He merely spreads your labia with two fingers, and the appendage wriggles its way inside of you all by itself. It feels strange, to have something so flexible move against your sensitive walls. You can feel yourself clench against the thick appendage with every little shift it makes. 

Doctor Gaster exhales a low sigh as he pushes himself slowly into you. You’re holding your breath, not wanting to give him the satisfaction of prying more moans out of you. It’s hard though. His cock is stretching you out more and more the deeper he pushes inside, and the texture of it, whispy and wet with a sturdy centre, stimulates your vaginal walls in a way you’ve never experienced before, giving you both a ticklish, teasing sensation and the primal satisfaction of a sturdy girth filling you up. 

When his hips meet yours and he’s as deep inside you as he can possibly go, he moans quietly and you shudder. 

“Before I forget. I have already added a fertility enhancer to your drip before you woke up, to optimise the chances of your pregnancy. Still, I believe we should take all the possible steps to maximise our chances,” Doctor Gaster says, his voice sounding a bit more rough now that he’s inside you. “I would like you to swallow these pills. They will cause your body to be even more receptive to my semen. They come in different flavours; would you prefer cherry, banana or apple flavour?”

He pulls several small pills out of the pocket of is lab coat, coloured in green, red and yellow. 

“Well?” He asks after you’ve only breathed heavily for a minute or so.

“A-apple,” you croak out.

“Good choice,” the doctor comments, bringing one of the green pills to your mouth. It tastes of apple and of the lube and rubber of the gloves. You swallow it obediently, long past trying to resist. It’s far easier to just go along with it. 

“Open your mouth.”

You open it. 

“Lift your tongue.”

You do. 

“You have swallowed it. Good. I am pleased to see that you have decided to be obedient, subject five.” He gives your cheek a condescending pat. “It really does make the process easier. I will now commence with the insemination.”

You’ve cooled down a bit while he was talking despite him being fully inserted in you, but when he slowly starts to move in and out of you, you can feel the pleasure picking up again immediately. His thick tentacle is moving against your inner walls as he pushes in and out of you, stroking the sensitive tissue. You can’t hold back your moans, approaching your climax rapidly as he repeatedly fills you.

Doctor Gaster leans over you until his upper body is pressed against yours, his hips still moving. The sensation of the smoky outer shell of his body ghosting against your skin on your stomach and your breasts adds to the heated, forbidden pleasure of it all. 

“I have taken the same fertility drug I have given you, you know,” Doctor Gaster whispers into your ear, his face now pressed against yours. “To increase the amount of semen to fill you with. I wanted to make sure I would have enough sperm for you.”

He makes a twisting motion with his hips, his half-solid, half-incorporeal flesh pressing against your clitoris, eliciting another deep moan from you. 

“I want you to pay attention when I ejaculate inside of you. I am willing to bet you will be able to feel the difference compared to any humans you might have been with.”

His motions get faster, the movements of his tentacle inside you more urgent, pressing harder against your walls. The heat becomes unbearable, but then he stills. 

“No. Not yet. You may only climax once I begin ejaculation. I explained about the process of facilitating the pregnancy. You must understand that we need to coordinate to achieve the optimal result.”

You start to cry. Your body is desperate for release and with all the straps holding you in place, you can’t do a thing to achieve it for yourself. As if you aren’t helpless enough already, you can’t even speed up the process to get it over with sooner. 

“Shhh, there there. I am only doing this for the best results. You will be allowed to climax soon, you just have to be patient.” 

The low voice against your ear does nothing to help you calm down. You continue sobbing while he keeps talking, waiting for you to cool down. 

“If the insemination is not immediately successful, we might try other methods,” Doctor Gaster tells you. “Maybe then we can try multiple orgasms and see if that helps you get pregnant faster. But for now, we are going to go with the optimisation of a single climax.” 

“P-please…” you stutter, your voice breaking on the word. 

“If you approach climax too soon again, I will have to stop,” the doctor warns you. But he does begin to move again, immediately going back to a faster-paced thrusting. You moan and sob in relief as his girth stimulates you, although this time his tentacle stays away from the most sensitive spots inside you. His own breathing is far less steady soon, and he starts groaning into your ear. 

Doctor Gaster lifts his head away from you and looks down at your face while his hips pick up an even faster pace, slapping against your flesh with every movement. There’s a flush on his face and a hungry, greedy look in his eyes. He loves seeing you like this, you realise, helpless and desperate and crying underneath him. 

“Look at me,” he commands, his voice no longer gentle. “Look me in the eyes.” 

You try to blink your tears away and follow his orders, a broken moan escaping you when you make eye contact at the same instant he thrusts into you especially hard. 

“Yes… yes…!” 

You can feel his motions get stuttery and less steady and immediately the press of the tentacle inside you is back, massaging your insides.

You cry out loudly at the waves of pleasure that rush through you.

Doctor Gaster slams into you a few more times and then he starts shuddering and his cock twitches inside you. You can feel a hot liquid squirting into you and then you’re following him, your walls clenching as your body shudders with the intensity of your release. You scream yourself hoarse when the feeling doesn’t abide as fast as you’re used to, the climax prolonged by his continuing thrusts and the massage of your most sensitive spot. All the while his ejaculation hasn’t stopped yet, obscene amounts of semen flooding you.

Finally, the doctor collapses on top of you, entirely spent. The both of you do nothing but breathe deeply for a short moment.

Then he nuzzles his mouth against the crook of your neck and begins to cover your face in kisses. 

“I love you,” he croons. 

You sigh deeply, the aftermath of your orgasm causing the sound to come out more like a moan than something annoyed. 

“Dammit, Gaster. You could have stayed in character a little bit longer,” you pout. 

“No,” he says, gently kissing your eyelids. “This was our first rough scene. I don’t want to drag it out for too long. Are you alright?”

“I’m fine,” you reassure him. Despite the reassurance, he slowly slides out of you. “Gaster, really…”

He’s already moving off you, undoing the straps that keep you in place and taking a close look at the skin where you were held. He removes the gloves from his hands and runs his hands over the skin carefully.

“It appears that the leather has not left any abrasions… good.” 

“It’s really okay,” you say. 

“The manuals on human intercourse state that it is important to provide physical and emotional aftercare after engaging in bondage and disturbing scenarios,” Gaster says seriously. “I will not skip out and risk harming you.”

You can’t help but giggle at the way he’s phrasing it. “Okay, fine. What exactly did your manuals say about handling my fragile human after-sex emotions?”

“Please do not make fun of me,” Gaster insists. “It said that I should provide water and food to ensure that you will not be dehydrated and low on energy, and that a hot bath will help your muscles relax. It also said that a soothing and nurturing approach would help ensuring that no emotional harm will follow as the result of our rough play. Then, we are supposed to talk about what we did, what we liked and what we didn’t like. In that order.”

“Fine. Slather me in that good old aftercare then, manual man.”

“I shall,” he says haughtily, picking you up princess-style. 

You’re still giggling when he carries you to the bathroom. Maybe you’re okay with his insistence on the extensive aftercare. 

It’s cute.


End file.
